wasting my time porting this?

[baja200merk]

Captain75 on here cut finger ports with a 1/2" electric belt sander and they came out nice.

[canuckr]

First post. But I agree with the guy that said to check out the macdizzy forum. It's all guys of varying skill and experience that tune engines. Lots of stuff that doesn't exactly pertain to outboards. But really good information. Just start reading. Lots. Don't be afraid to grind on an engine. You'll never learn if you don't try.
I've quite heavily ported some dirt bike engines. I've scrapped 2 cylinders. Ooops. Get a new one. Try again.

[baja200merk]

I have a few junk fingerported 3.0 sleeves laying around if you want I can send you one to use as a template for cutting your finger ports.

[NosBoss]

That's all I've been doing is reading. Lol

Thanks for the offer baja. I have one cylinder marked out for fingerports right now. I haven't figured out exactly how I'm going to do it yet. This block doesn't have fingerport bosses so they will have to be shallow. I've been working on chamfering the ports and it's taking a while.

[baja200merk]

Make them wide

[powerabout]

Its an art with some complex science attached.
Just read a forum on a sled racer where he was saying the diameter of the end of his pipe determines the size of the squish band in the combustion chamber and we wonder how they make so much hp/ci

[dwilfong]

the port map is a good tool. The angle of the front of the transfer port closes to the ex is a good tuning tool for a specific RPM. the farther theses two angles meet to the front of the cyl will increase top end power. You cant go to much closer than have them meet at the center of the cyl. As this will let to much get sucked out the ex to soon.

I have found that a 30 deg difference between when the ex opens and the transfers open will give the best all around performance on the eng I have played with.
Their are a few different programs out there that will let you do the timings with just measurements of the ports and the rod length using the boar and stroke also combined with the piston to deck hight.
You can make all the cuts and know what the timing will be. This way you can decide what timing you will have before you ever assembly the eng.
For those that are interested I have a Excel Doc that I can Email that will do every thing you will ever need. It can also calculate proposed HP.

[NosBoss]

Ok, the block is going into work with me tomorrow to be cleaned in the hotsy parts washer for the first time. It's got too much crap in it for me to see anything. Once it's clean, I'll go over all my chamfering to make sure it's all good and maybe do some clean up. I still have not cut any finger ports. I don't feel comfortable doing it free hand and i haven't figured out a jig yet. Still working on that. I have plenty to do to the front half to keep me busy while i figure something out. Oh, i have a rigid hone on the way to correctly hone it.